This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 7 |
| 3 | -139 |
| 4 | 5227 |
| 5 | -317491 |
| 6 | 28352347 |
| 7 | -3495615859 |
| 8 | 568791063547 |
| 9 | -118065959980051 |
| 10 | 30445266606199387 |
| 11 | -9547490385298102579 |
| 12 | 3578014749635903623867 |
| 13 | -1579193384981544127824211 |
| 14 | 810752966831581612807206427 |
| 15 | -479049438742420410992820125299 |